CAREER: Rheological Evolution of Subduction Interface Shear Zones: Insights From Exhumed Subduction Complexes

职业：俯冲界面剪切带的流变演化：来自挖掘出的俯冲复合体的见解

• 批准号: 1555346
• 负责人: Jaime Barnes
• 金额: $ 19.9万
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2019-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1555346&HistoricalAwards=false
• 关键词: CAREER; Rheological; Evolution; Subduction; Interface

Geophysical data from subduction zones worldwide illustrate that subduction interfaces are rheologically complex and heterogeneous. Observations of exhumed remnants of subduction interface shear zones yield fundamental insight into the processes that control this complexity. The scientific objective of this project is to systematically investigate the rheological properties and evolution of the subduction interface using exhumed rocks. Specifically, the project will investigate the heterogeneity of deformation within subduction interface shear zones and the nature of changes in deformational styles and mechanisms as rocks are progressively subducted to depth. The research component of this project will focus on three exhumed subduction shear zones that each record prograde deformation and that together represent a wide range of pressure-temperature conditions. The field sites include the: 1) Chugach accretionary complex, Alaska (T = 150-300 degrees C, P = 2-5 kilobars), 2) the Condrey Mountain Window, southern Klamath Mountains, northern California (T = 300-420 degrees C, P = 5-7 kilobars), and 3) the Cycladic Blueschist Unit in Syros Island, Greece (T = 450-550 degrees C, P = 2-15 kilobars). The project uses a wide range of structural, microstructural, and petrological tools to track macro-scale distributions of strain, degrees and mechanisms of strain localization, fluctuations in fluid pressures and strain rates, microphysical mechanisms of rock creep, effects of metamorphic reactions on deformation, and sources of anisotropy, in rocks that have been cycled through the subduction process. The research involves: 1) identifying domains in each field area that represent deformation under prograde conditions; 2) documenting macro-scale strain distributions; 3) determining the microphysical mechanisms of rock creep in different rock and mineral phases; and 4) synthesizing the field and microstructural observations in the context of subduction zone mechanics. The integrated educational objective of this CAREER award is to establish a five-year mentoring and research program at the University of Texas ? the Jackson School of Geosciences-Catalyst (JSGC) ? aimed at ethnic and racial minorities and first-generation college students in the Earth Sciences. JSGC will provide 1) mentoring, community support, and career advice for undergraduates through mentorship pairing, monthly meetings, social events, and field trips; and 2) financial support for members while simultaneously enhancing their undergraduate research experience through summer internships, senior thesis projects and participation in field-based team research. The JSGC program is designed to increase retention and completion rates of underrepresented minorities in STEM fields and to prepare and encourage these students to go on to graduate school.Processes in the zone between a subducting oceanic plate and the overriding plate ? the subduction zone interface - are responsible for a all-too-familiar yet poorly understood phenomena such as large devastating earthquakes as well as other more enigmatic events such as episodic slip and tremor. This project aims to improve understanding of this zone through a systematic study of terranes that were exhumed from the depths of the interface by various tectonic processes. These terranes provide an unusual opportunity to understand the geologic processes associated with the various phenomena along the subduction zone interface. Additionally, the project will advance desired societal outcomes through: (1) full participation of women and underrepresented minorities in STEM through support of an early career Hispanic female PI, a female graduate student, and, most notably, a robust plan to provide mentoring, and research and professional development opportunities to underrepresented minorities majoring in Earth Science, thus directly contributing to retention and promotion of underrepresented minorities in STEM fields; (2) development of a diverse, globally competitive STEM workforce through undergraduate and graduate student training with emphasis on mentoring students from underrepresented groups in Earth science; and (3) increased partnerships through international collaboration.

来自全球俯冲区域的地球物理数据表明，俯冲界面在流变学上是复杂且异质性的。对俯冲界面剪切区的挖掘残留物的观察产生了控制这种复杂性的过程的基本洞察力。该项目的科学目的是系统地研究俯冲界面的流变特性和俯冲界面的演变。具体而言，该项目将研究俯冲界面剪切区域内变形的异质性，以及随着岩石的逐渐俯冲到深度，变形样式和机制变化的性质。该项目的研究组成部分将集中在每个记录的俯冲剪切区域，每个记录的剪切区域，并共同代表了广泛的压力温度条件。野外场地包括：1）阿拉斯加的Chugach增生综合体（t = 150-300度C，p = 2-5千射线），2）2）北加州克拉马斯山脉南部的康德里山窗（T = 300-420度） C，P = 5-7千射线）和3）希腊Syros Island的Cycladic Blueschist单元（T = 450-550摄氏度，C，P = 2-15千射线）。该项目使用多种结构，微观结构和岩石学工具来跟踪应变，劳累定位的菌株，程度和机制的宏观尺度分布，流体压力的波动和应变速率，岩石蠕变的微物理机制，变形反应对变形的影响和各向异性的来源，在俯冲过程中循环的岩石中。研究涉及：1）识别每个野外区域中代表变形条件下变形的域； 2）记录宏观尺度的应变分布； 3）确定不同岩石和矿物相中岩石爬行的微物理机制； 4）在俯冲区力学的背景下综合了田地和微观结构观测。该职业奖的综合教育目标是在德克萨斯大学建立五年的指导和研究计划？杰克逊地球科学 - 催化剂学院（JSGC）？针对地球科学的少数民族和种族少数民族和第一代大学生。 JSGC将通过指导配对，每月会议，社交活动和实地考察为大学生提供指导，社区支持和职业建议； 2）为会员提供财政支持，同时通过暑期实习，高级论文项目和参与基于现场的团队研究，同时增强了他们的本科研究经验。 JSGC计划旨在提高STEM领域中代表性不足的少数族裔的保留率和完成率，并准备并鼓励这些学生继续上学。俯冲带界面 - 负责一个非常熟悉但知之甚少的现象，例如大型毁灭性地震以及其他更神秘的事件，例如情节性滑移和震颤。该项目旨在通过对界面深处通过各种构造过程从界面深处挖掘出来的地层的系统研究来提高对该区域的理解。这些地形提供了一个异常的机会，可以理解与俯冲带界面沿着各种现象相关的地质过程。此外，该项目将通过：（1）通过支持早期职业西班牙裔女性PI，一名女性研究生，以及最著名的是提供指导，指导，提供指导，指导，以及在地球科学领域主修少数群体的研究和专业发展机会，因此直接有助于保留和促进STEM领域代表性不足的少数民族； （2）通过本科和研究生培训发展多样化的全球竞争性STEM劳动力，重点是指导地球科学中代表性不足群体的学生； （3）通过国际合作增加了伙伴关系。